of detroit



March 8,V 1932. M. A. POWERS BURNER CONTROL MECHANISM Filed Feb. 24, 1930 ATTORNEYS Patented Mar. 8, 1932 UNITED AsTaJrEs PATENT, OFFlcE MILTON A. POWERS, OF DETROIT, MICHIGAN, ASSIGNOB TO THE TIMKENDETROIT COM- PANY, OF DETROIT, MICHIGAN, A CORPOQATION OE MICHIGAN BUnNEn'coNrnoL kvarizonaNrsat application med February 24,*1930. serial No. 430,936.

The invention relates to burner control mechanisms such as are used in connectlon with oil or gas burners and has pa'rtlcular reference tothe means for stoppmgthe burner in case of failure to ignite or upon failure of combustion after ,ignition has taken'vvplace. Where electric or gas ignition is usedbit is customary to maintain the 1gn1- tion circuit for a sufficient length of timeto insure ignition but it is desirable to cut olf the current as soon as the fuel is. lighted. These objects have been accomplished by using radiant energy from the flame for operating al thermostat that controls the running and ignition circuits. 'It is, however, necessary' that the thermostat should beso placed as to -receive the radiant energy and this With many constructions of furnace is difficult to accomplish. For instance, -in the round boiler type of' furnace it is usual to construct a hearth at the grate level of the boiler and to place the oil spraying nozzle lcentrally above this hearth. In this case the most feasible location for the control device which lmust be directly in the path of `the radiant energy, is inthe iredoor of the boiler. Such a position is not desirable as the firedoor is opened from time to time and the loose cable connections to the device are snb ject to damage. A position for the device within the combustion chamber near the hearth level is much ,to be desired but has been impossible to attain due tothe intense heat which would destroy the usual control device, and also the interference which such a device would introduce'to the operation of the burner.

It is the purpose of the present invention to avoid the above described difiiculties by a construction in which the control device is effectively' shielded from the heat of combustion. does not project into the combustion chamber Where it might interfere with the operation of the burner, and in addition may be attached directly to the burner unit thus greatly simplifying the installation and wiring. At the same time the heat sensitive mechanism of the device is fully exposed to radiant energy from the llame. With these objects in View the invention'co'nsists. intlie construction as hereinafter set forth. In the drawings: Figure l is a vertical central section through a. portion of an oil .burning furnace showing my improved construction of thermostat in relation'thereto; l

`lifigure 2 is a plan view. v As shown, A is the inner Wall ofthe boiler, B a. refractoryk hearth at the base of the boiler provided with the annular lgrooved ring C against `which th-e liquid fuel spray is' directed from a revoluble sprayer nozzle D arranged centrally of the hearth andA o erated by an electric motor E beneath the hearth, these parts being of any suitable construction. Located in the hearth at a point intermediate the nozzle D and the ring C is a recess in which is placed a housing F extending downward and laterally outward beneath the hearth. The outer wall of this housing in the portion G thereof passing through the hearth is bevelled so as to leave an unobstruct` ed path for the heat rays from the flame and at the same time to form a shield for covering the portion H of the housing;- extending radially outward vbeneath the hearth. In this shielded portion of the housing I arrange a thermostat I which as shown is vin the form of a spirally bent bar of composite metal, its outer end being anchored at J and its-inner Isn end attached to a revoluble shaft K. These parts are'. mounted on a plate L which is de- .tachably secured to cover an opening at the radially outward end of the housing F, the said shaft K passing through-the plate and having on its outer end a circuit closing switch. This is preferably a mercury switch comprising a glass tube M having electrodes extending thereinto and a sufficient quantity of mercury' to electrically connect these electrodes when the tube is tilted in one direction. The switch may be protected by a housing N enclosing the same and outside of the plate L.

lVith the construction as thus far described the thermostat I is out of the direct path of radiant energy and therefore Would not be effected by the turning on or olf of the flame.

have, however,- arranged a ree'cting mirror Oon the inner wall ofthe-recess inthe hearth and in such position and at such angle vas to direct the lradiant Aenergy vfrom the `flame upon the thermostat I. Preferably'thsmir- :ror .is concave as illustrated in Figure-2150- that the heat raysy are concentrated uponthe thermostat. .Thusiinoperation'wheneverthe fuel isignited the flame extendingupward from the ringC `will radiate heat :whichfally ing upon the kmirror O will Ibe directedfto` wards and concentrated upon thethermostat I so as to bring' about an almost instantaneous` response. This will cause lthe tilting othe vtube N e'ecti'ng either the closing or lthe opening of an .electric circuit'which controls thel operation of the burner and r cuts ofthe current 4supply r4thereto under abnormal conditions; A y

. The lower portion'of'the'housing F is preferably hopper shaped and is `provided with anopening at'its lower end normally -closed by a plate P. This constitutesareceptacleffor collecting any dirt vwhich may fall into the opening in the hearth and `which from time to time may be removed by detaching fthe plate P.

What I claim as my invention is z 1. The 'combination with an intermittently 'operated fuel burner and a control circuit therefor, of a Vhearth beneath said burner having a small aperture therethrough, a'thermostatically operated mechanism for controlling said circuit :located beneath said hearth at one side `o1" said aperture, and a reflector located to Lreceive through said aperture radiant heat from the flame and :to redirect the same upon said thermostatic element.

2. The conbination with an intermittently operated fuel burner and a control circuit therefor, of a hearth beneath the burner having a small aperture therethrough, a thermostatically actuated mechanism for controlling said circuit located beneath said hearth at one side of said aperture, `a reflector for receiving through said aperture radiant heat from the flame and redirecting the same upon said thermostat, v'and a housing for enclosing said thermostatically operated mechanism.

In testimony whereof I aliix my signature.

MILTON A. POWERS. 

